This invention relates to an image data transferring system, an image data transferring apparatus and a method thereof for efficiently transferring image data including a GUI (graphical user interface) image through a network.
It has been popularly practiced to transfer image data via a network and display the transferred data for example, by connecting a personal computer to the internet to display image data from the world wide web (WWW). For example, PUPA 8-130656 discloses an invention to change the number of colors of image data depending on the movement of an image. Image data generally contains a large amount of data and needs a long time for being transmitted via a network. For this reason, when an image containing many changes is transmitted, the bandwidth (transmission rate) of the network cannot follow the change of the image, inducing a problem that the display of the image is disturbed or the movement of the image is not natural. In order to solve such a problem, it may be considered to apply the invention disclosed in the aforementioned Japanese reference relating to a method for taking in a color image to the transmission of image data. However, the method described therein discloses none of the technical matters required for applying it to the transmission of image data via a network. Even if the described method could be applied to image data transmission, a user would have to continually pay attention to the change of the image and change the number of colors of the data every time the degree of the change of the image varies.
The present invention is conceived in view of the problem of the prior art described in the above and aims at providing an image data transferring system, an image data transferring apparatus and a method thereof for efficiently transferring image data via a network.
It is, therefore, an object of this invention to provide an image data transferring system, an image data transferring apparatus and a method thereof which can optimize the quality of an image and the change of the image depending on the bandwidth (transmission rate) of the network by adjusting the amount of image data depending on the change of the image, i.e., transmitting more images with less amount of data when images of many changes are transmitted while transmitting a high quality image with a larger amount of data when the change of the image is less.
It is another object of this invention to provide an image data transferring system, an image data transferring apparatus and a method thereof which can automatically switch between an image of reduced color and an image of color which is not reduced for displaying the image, without requiring the user to monitor the change of the image and operate depending on the change.
It is yet another object of this invention to provide an image data transferring system, an image data transferring apparatus and a method thereof which can adjust the amount of image data depending on the movement of the image and transmit an image of a necessary and sufficient quality from a transmitting side to a receiving side to reduce the load on a server device supplying the image data and reduce the load on the network.
These and other objects are realized by the present invention comprising an image data transferring system for transferring data from an image data transmitting apparatus to an image data receiving apparatus, said image data transmitting apparatus comprising; reduced data generating means for generating reduced data by reducing the amount of data of continuously inputted image data (input data), delta data generating means for generating image data of the delta between said input data and said reduced data (delta data), delta detection means for detecting a delta between consecutive ones of said input data, and image data transmitting means for transmitting to said image data receiving means said transmission data with identifier data attached thereto indicating that it is said delta data when no delta is detected between consecutive ones of said input data for a predetermined period and transmitting said transmission data with identifier data attached thereto indicating that it is said reduced data when a delta is detected between consecutive ones of said input data for a predetermined period, said image data receiving apparatus comprising; transmission data receiving means for receiving said transmission data, and image displaying means for displaying an image indicated by said reduced data included in said transmission data when said identifier data of the received transmission data indicates that it is said reduced data, and displaying the image indicated by said reduced data with the image indicated by said delta data added thereto when said identifier data of the received transmission data indicates that it is said delta data.
This invention also provides an image data transferring apparatus for transmitting transmission data to an image data receiving apparatus which receives said transmission data and displays, when said identifier data of the received transmission data indicates that it is reduced data, which is image data consecutively inputted to said image data transmitting device (input data) subtracted by a data amount, an image indicated by said reduced data included in said transmission data, and displays, when said identifier data of the received transmission data indicates that it is delta data which is the delta between said input data and said reduced data, the image indicated by said reduced data with the image indicated by said delta data added thereto, said image transferring apparatus comprising; reduced data generating means for generating said reduced data, delta data generating means for generating said delta data, delta detection means for detecting a delta between consecutive ones of said input data, and image data transmitting means for transmitting to said image data receiving apparatus said transmission data with identifier data attached thereto indicating that it is said delta data when no delta is detected between consecutive ones of said input data for a predetermined period and transmitting said transmission data with an identifier data attached thereto indicating that it is said reduced data when a delta is detected between consecutive ones of said input data for a predetermined period.
Preferably, said reduced data generating means generates reduced color data having data amount reduced by reducing the number of colors of said input data as said reduced data, said delta data generating means generates said delta data indicating the delta between said input data and said reduced color data, said delta detection means detects said delta when there is a delta between said input data and the input data inputted before or after said former input data, and said image data transmitting means transmits said reduced color data or said delta data with said identifier data added thereto as said transmission data depending on whether or not a delta is detected in the input data.
Preferably, said image data receiving apparatus displays the image indicated by said reduced data with an image indicated by reduced data which is received later than said former reduced data added thereto, said delta data generating means stores said inputted input data (first input data) to generate input delta data indicating a delta between said stored first input data and input data which is inputted after said stored first input data (second input data) and generates said reduced color data by reducing the number of colors of said generated input delta data, and said delta data generating means reduces the number of colors of said stored first input data to generate said delta data by taking the delta between said first input data and said color reduced first input data.
The image data transmitting apparatus of this invention transmits transmission data for displaying an image without reducing the number of colors thereof when there is no delta in the image over a predetermined period, and transmission data for displaying the image with the number of colors reduced when there is a delta in the image in the predetermined period to an image data receiving apparatus having a specific function for display therein via an arbitrary communication network such as LAN, an ISDN communication network, or the internet.
An image data receiving apparatus which displays an image transmitted from the image data transferring apparatus of this invention is required to have a function to generate an image from the transmitted data and display it as described hereunder. The image data receiving apparatus receives via a communication network transmission data transmitted from a transmitting side (image transferring apparatus). The transmission data is associated with identifier data indicating whether the image data included in the transmission data is color reduced data of an image in which the number of colors of an original image, which is not color reduced (full color image), are reduced to 16 colors (color reduced image) or delta data which is used to generate a full color image by adding it to the color reduced image so far displayed in the image data receiving apparatus. The image data receiving apparatus displays an image based on the identifier data associated with the transmission data. Specifically, the image data receiving apparatus generates an image indicated by color reduced data when the identifier data indicates color reduced data while it generates a full color image by adding an image indicated by delta data to a color reduced image so far displayed when the identifier data indicates delta data for display in a display device such as a CRT display.
When the transmitting side color reduces only the delta between changing images to transmit color reduced data in order to reduce the data amount of transmitted data, the image data receiving apparatus adds the image of the newly received color reduced data to the color reduced image so far displayed when color reduced data is received in the manner similar to the case when delta data is received.
In the image data transferring apparatus, the reduced data generating means reduces the number of colors of the image of full color image data of 24 bits per pixel to 16 colors to generate reduced data (color reduced data) in which the data amount is reduced to 4 bits per pixel. Alternatively, the reduced data generating means takes the delta between 2 frames which are consecutively inputted and assumes a change and further color reduces the delta into color reduced data. The reduced data may be generated by another method such as by eliminating data from the original image data. The inputted data may be continually inputted in a given period in the manner, like animation image data, or the changed portion may be continually but irregularly inputted in response to an operation by a user in the manner like a GUI image.
The delta data generating means generates differential image data indicating the delta between a full color image data and a color reduced image data. The delta detecting means takes the delta between full color image data for 2 frames consecutively inputted, for example, and determines that there is no delta between full color image data for the 2 frames when there is no delta or when an accumulation of the absolute value of the delta of each pixel is below a given threshold value.
The image data transmitting means determines that there is no delta, or there is a small delta in an image when a delta is not detected between consecutive p frames (p is an integer arbitrarily set) or when a delta is not detected in a given period, for example, and associates the delta data, which includes a larger data amount in comparison to the color reduced data and consumes longer time for transmission with identifier data which indicates that the data to be transmitted is delta data, to generate transmission data which causes a relatively small number of images to be displayed in the receiving side (image data receiving apparatus) in a given time for transmission to the receiving side.
Conversely, when a delta is detected between the images in a given period, the image data transmission means determines that the images involve a substantial change and associates the color reduced data, which includes a reduced data amount in comparison to the delta data and consumes shorter time for transmission with identifier data which indicates that the data to be transmitted is color reduced data, to generate transmission data which causes a relatively large number of images to be displayed in the receiving side in a given time for transmission to the receiving side.
This invention provides an image data transferring method for transferring data from an image data transmitting apparatus to an image data receiving apparatus, said method comprising the steps effected in said image data transmitting apparatus of: generating reduced data by reducing the amount of data of continuously inputted image data (input data), generating image data of the delta between said input data and said reduced data (delta data), detecting a delta between consecutive ones of said input data, and transmitting to said image data receiving apparatus said transmission data with an identifier data attached thereto indicating that it is said delta data when no delta is detected between consecutive ones of said input data for a predetermined period and transmitting said transmission data with an identifier data attached thereto indicating that it is said reduced data when a delta is detected between consecutive ones of said input data for a predetermined period, and the steps effected in said image data receiving apparatus of: receiving said transmission data, and displaying an image indicated by said reduced data included in said transmission data, when said identifier data of the received transmission data indicates that it is said reduced data, and displaying the image indicated by said reduced data with the image indicated by said delta data added thereto when said identifier data of the received transmission data indicates that it is said delta data.
This invention also provides a recording medium recording a program which causes a computer to execute in an image data transferring apparatus for transmitting transmission data to an image data receiving apparatus which receives said transmission data, displays, when said identifier data of the received transmission data indicates that it is said reduced data which is image data consecutively inputted to said image data transmitting device (input data) subtracted by a data amount, an image indicated by said reduced data included in said transmission data, and displays, when said identifier data of the received transmission data indicates that it is full color image data indicating the image of said input data, the image indicated by said received transmission data with the image indicated by said full color image data added thereto, said program comprising a reduced data generating step for generating said reduced data, a full color image data generating step for generating said full color image data, a delta detection step for detecting a delta between consecutive ones of said input data, and an image data transmitting step for transmitting to said image data receiving apparatus said transmission data with an identifier data attached thereto indicating that it is said delta data when no delta is detected between consecutive ones of said input data for a predetermined period and transmitting said transmission data with an identifier data attached thereto indicating that it is said reduced data when a delta is detected between consecutive ones of said input data for a predetermined period.
Preferably, said full color image data is delta data of a delta between said input data and said reduced data and said image data receiving apparatus displays an image indicated by said reduced data with an image indicated by said delta data when said identifier data indicates said delta data, said medium recording a program which causes said reduced data generating step to execute a process of generating color reduced data having a data amount reduced by reducing the number of colors of said input data as said reduced data, causes said full color image data generating step to execute a process of generating said delta data indicating the delta between said input data and input data inputted before or after the former input data, causes said delta detecting step to execute a process of detecting said delta when there is a delta between said input data and input data inputted before or after the former input data, and causes said image data transmitting step to execute a process of transmitting said color reduced data or said delta data with said identifier data associated thereto as said transmission data depending on whether or not a delta is detected in the input data.
Preferably, said image data receiving apparatus displays an image indicated by said reduced data with an image indicated by reduced data received later than said former reduced data added thereto, said program causes said reduced data generating step to execute a process of storing said input data inputted (first input data) to generate input deferential data indicating a delta between said stored first input data and input data inputted later than said stored first input data (second input data) and generate said color reduced data by reducing the number of colors of said generated input delta data, and causes said full color image data generating step to execute a process of reducing the number of colors of said stored first input data to generate said delta data by taking a delta between said first input data and said color reduced first input data.